Tube rolling mill for producing thin walled tubes



Sept. 9, 1969 J. J. VERDICKT TUBE ROLLING MILL FOR PRODUCING THIN WALLEDTUBES Filed July 21, 1966 4 Sheets-Sheet l INVENTOR Jacq ues JosephVerdickt Sept. 9, 1969 .1. J. VERDICZKT TUBE ROLLING MILL FOR PRODUCINGTHIN WALLED TUBES Filed July 21. 1966 4 Sheets-Sheet 2 INVENTOR JacquesJoseph Verdickt P 9, 1969 J- J. VERDICKT 3,465,563

TUBE ROLLING MILL FOR PRODUCING THIN WALLED TUBES Filed July 21, 1966 4Sheets-Sheet 5 FIG 5 14 2a 2 n I, o 14!! 8 o I \u I 7 10 1! i O Q J 9 2"I v 10: If O 21 9" I Q o 14 /V./,:// I I 1 4 on g INVENTOR JacquesJoseph Verdicki P 1969 J. J. VERDICKT 3,465,563

TUBE ROLLING MILL FOR PRODUCING THIN WALLED TUBES Filed July 21, 1966 4Sheets-Sheet 4 FIG. 6

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INVENTOR Jacques Joseph Verdick! United States Patent 3,465,563 TUBEROLLING MILL FOR PRODUCING THIN WALLED TUBES Jacques Joseph Verdickt,Malo-les-Bains, France, assignor to Societe Anonyme dite: Vallourec,Paris, France Filed July 21, 1966, Ser. No. 566,803 Claims priority,applicgtsit iiu1 France, July 23, 1965,

Int. c1.1iz1b 19/06 U.S. CI. 7296 8 Claims ABSTRACT OF THE DISCLOSUREThis invention relates to a new rolling mill which can be used for themanufacture of metal tubes, particularly steel tubes.

It is known that for the purpose of producing a tube of this type thestarting material is generally a billet which is pierced at its centreto form a blank, into which a mandrel is introduced, and which isengaged between the rolls of the rolling mill, which are usually threein number and which give rise to a forced reduction of the thickness ofthe tubular blank.

The rolls are bodies of revolution which are driven rotationally by asuitable device and which, viewed in the direction of rolling, have insuccession a conical portion efiecting the engagement of the blank, andthen a portion having a fairly abrupt increase in diameter which effectsthe actual rolling, and finally a substantially cylindrical portionwhich effects the smoothing of the outer surface of the tube.

It is also known that rolling mills comprising three rolls of this typedo not make it possible to produce industrially tubes having a slightthickness in relation to their diameter.

For example, with mills of this type it is generally possible to produceonly tubes in which the ratio of the outer diameter to the thickness ofthe tube is between 4 and 11.5.

In practice, it is found that when it is desired to obtain smaller tubethicknesses, the difiiculties arise in the rolling of the terminalportion of the blank because the great reduction of thickness producedby the rolling gives the tube section (which, since it is its end whichis involved, can be held only by a rigid portion situated upstream ofthe rolls) a trilobate shape which very rapidly leads to the jamming ofthe blank or to its tearing, and frequently damages the rolling mill.

The method according to the invention ensures that the rolling millautomatically presents a diiierent adjustment depending on whether it isworking on the body of the hollow blank which it is rolling and thethickness of Which it is considerably reducing, or whether it is workingon the end of the blank, in which case it gives rise only to a smallerreduction of the thickness of the blank, while imparting to the latteronly a reduced speed of advance.

The present invention has an object a new method of rolling thin tubes,said method being essentially charac- "Ice terised by the fact that thetubular blank is rolled in a rolling mill in order to give it therequired thickness over the greater part of its length, whereupon thereduction of thickness of the tube obtained by rolling is reduced nearthe end of the blank.

In one particular embodiment of the invention for the rolling of steeltubes, a short portion, for which the ratio of the diameter to thethickness of the tube is lower than about 11, is left at the end of theblank.

In a preferred embodiment a reduction of the spacing of the rolls isalso effected during the rolling of the end of the tube.

The present invention has as object the new industrial productconstituted by a rolling mill for thin tubes, which is essentiallycharacterised by the fact that each roll is mounted by two bearingscomprising swivel-joints or similar devices, on the one hand on a platewhich is fixed in relation to the frame of the rolling mill and on theother hand on a movable plate the angular position of which in relationto the fixed plate can be varied with the aid of any means, in order tobring to a smaller value the reduction of thickness during the rollingof the end of the tube.

In a preferred embodiment of the invention, each swivel-joint bearingsupporting a roll is mounted by its plate in such a manner as to be ableto move radially in relation to the latter, each roll being held in theworking position by means of counter-pressure acting on a piston solidto the bearing, in such a manner that the roll cylinders can moveautomtically apart from one another when they are subjected to abnormalstresses.

The present invention likewise has as object a particular form ofexecution of the method indicated hereinabove, with is characterised bythe fact that the reduction of thickness of the tube at the end of thelatter is limited by pivoting the two plates of the rolling mill whichhas just been described in relation to one another.

Finally, the present invention has as object thin tubes rolled by theabove-described method, said tubes being particularly characterised bythe fact that they have a zone of greater thickness at one of theirends.

One particular embodiment of the invention will now be described, whichwill illustrate in greater detail the different characteristics of theinvention.

The description of this embodiment, which is given solely by way ofillustration and without limitation in any way, refers to theaccompanying drawings, in which:

FIGURE 1 is a diagrammatical view in perspective showing how inaccordance with the invention the distances separating the rolls of therolling mill can be varied,

FIGURE 2 illustrates diagrammatically in section a rolled tube accordingto the invention,

FIGURES 3 and 4 illustrate diagrammatically the positions of the rollsof the rolling mill which correspond to the sections IIIIII and IV-IV inFIGURE 2,

FIGURE 5 is a front view, partly cut away, of a form of construction ofa rolling mill according to the invention, and

FIGURE 6 is a view in section on the line VI-VI in FIGURE 5.

In FIGURE 1, a roll 1 is diagrammatically illustrated which turns on twoswivel-joint bearings 2 and 3, which are situaed respectively on a fixedplate 4 and a movable plate 5.

Two other rolls (not illustrated) are mounted in the same manner onswivel-joint bearings 2', 2" and 3, 3".

According to the invention, the movable plate 5 is mounted to bepivotable about axis 6 which corresponds to the rolling axis of thehollow blank.

The movable plate 5 is provided with two movable stops 7 and 8 whichlimit its pivoting movement by bearing against the fixed stops 9 and 10,which may be adjustable.

The hydraulic or pneumatic device 11 has been shown diagrammatically,which enables the plate to be rotated in relation to the plate 4.

It is clear that when the angular position of the plate 5 in relation tothe plate 4 is varied, the distance between the roll 1 and the axis 6 islikewise varied. In fact, any pivoting of the plate 5 in relation to theplate 4 has the effect of varying the warping of the quadrilateralconstituted by the axis 6, the line 2-3, and the radii of the plates 4and 5 which pass respectively through the bearings 2 and 3 and throughthe axis 6.

Since through its construction the roll 1 is situated substantially inthe centre of the segment 23 it is obvious that any increase in thewarping of the quadrilateral previously defined has two effects, namelyof firstly reducing the distances between the roll 1 and the axis 6 andsecondly increasing the inclination of the axis of the roll 1 inrelation to the axis 6 and consequently of increasing the rolling pitch,that is to say the speed at which the blank is driven by the rolls.

It is likewise evident that any reduction of the warping of thequadrilateral in question will produce the reverse effects.

It will therefore be understood in these circumstances that if, afterthe position of the plate 5 has been adjusted (by adjusting the positionof the fixed stop 9), so as to obtain a sufficiently intensive rollingeffect to make the tube wall as thin as is desired, it is sufi'lcient,when the end of the rolling of the blank is reached, to utilise thedevice 11 to pivot the plate 5, which assumes the position illustratedin FIGURE 1, in order to move the rolls away from the axis 6 and leave agreater thickness on the terminal portion of the blank. Thedisadvantages which were mentioned hereinabove and which were inherentin previously known rolling mills are thus avoided.

In section in FIGURE 2 a tube rolled in the manner just described isillustrated, the greater part of the tube having a diameter D whichcorresponds to a relatively slight Wall thickness in relation to thediameter of the tube.

At the end of the rolling (towards the left-hand end of the tube) themovable plate has been pivoted in the direction of the arrows F (FIGURE3) in order to bring it from the position occupied in FIGURE 3 to theposition occupied in FIGURE 4, thus making it possible to reduce therolling effect and give the blank a diameter D greater than D In FIGURES5 and 6 the fixed plate 4, in relation to which the movable plate 5 isadapted to pivot by means of suitable bearings, is found once again.

These figures also illustrate the pairs of swivel-joint bearings 2-3,2'3', and 2"3", in which the shafts 12, 12, and 12" supporting the rolls1, 1, and 1 are mounted.

These shafts 12, 12', 12" are in turn driven rotationally bycorresponding drive shafts 13, 13, and 13", to which they are connectedthrough cardan points.

It can be seen in FIGURE 5 how the bearing blocks 14, 14', and 14" canslide radially in relation to the fixed plate 4. The same is true of thebearing blocks situated on the movable plate 5.

As can be seen clearly in FIGURE 6, the bottom portion 15 of eachbearing block constitutes a cylinder inside which a piston 16 ismovable, so that by delivering a fluid under pressure to the chamber 17thus formed it is possible to hold the roll in their working position(the bottom of the piston 16 striking against a corresponding shoulderon the cylinder 15) while permitting the rolls to yield in the event oftheir being subjected to excessive stressing, which would correspond inthe chamber 17 to a pressure higher than the pressure to which the fluidin question is adjusted.

This device can be operated for example by utilising an adjusted valvewhich allows the fluid to escape to the outside when the pressureexceeds a given value in the chamber 17.

The position of the rolls is adjusted by effecting the axialdisplacement of the piston 16 of each of the bearings with the aid of awheel 18 driven rotatably by a worm 19 and keyed on the threaded body ofthe piston 16 which engages in a fixed nut 20.

As can been seen in FIGURE 5, all the worms 19 controlling thedisplacement of bearings on the same plate are made solid to one anotherby bevel gears 21 and 22, so that the bearings 3, 3, 3" or 2, 2, 2 arealways acted on simultaneously so as to cause them to move the samedistances in relation to the axis 6 of the blank 23.

In FIGURE 6 is can be seen how the blank contains in its centre amandrel 24 against Which the rolling is effected.

FIGURE 5 shows how the pivoting of the movable plate 5 is effected withthe aid of the cylinder 25 which is articulated at 26 on the body of therolling mill and in which the piston 27 is movable, the rod of saidpiston being articulated at 28 at a point on the movable plate 5.

The pivoting is effected by delivering a fluid under pressure on one orthe other side of the piston 27.

In the embodiment illustrated in FIGURES 5 and 6, the movable stop 7bears against a fixed stop 9 which is adjustable through the fact thatit is mounted by a threaded body 9 in a nut 9 solid to the frame of therolling mill. A lock-nut 29 enable the fixed stop 9 to be locked in thedesired position.

In the embodiment illustrated in FIGURES 5 and 6, the other movable stop8 bears against a fixed stop 10 which in turn is supported against therod 10 of the piston 10" which moves in the cylinder 30.

A device of this type enables the stop 10 to be initially placed in theposition which corresponds to the position in which the piston 10" ispushed upwards, and then progressively to vary the position of the stop10, for example by delivering through a calibrated aperture the fluidcontained in the bottom portion of the cylinder 30, while a fluid underpressure is introduced into the top portion of said same cylinder 30 soas to move the piston 10" progressively downwards.

It will be understood that through this feature of the invention, orwith the aid of any suitable means enabling the movement of the stop 10to be adjusted in dependence on time or on the length of the tuberolled, it is possible to vary correspondingly the thickness of the tuberolled in this manner.

This feature makes it possible in particular to roll tubes of relativelyslight thickness in relation to their diameter, the rolling thicknessbeing abruptly brought to a normal value on the rear portion of thebank. The pivoting of the movable plate may for example be effectedautomatically in this case with the aid of a photoelectric cell whichdetects the passage of the rear end of the blank.

By effecting suitable displacements of the stops this feature of theinvention enables the tube to be given desired additional thicknesses atcertain points or even to produce tubes having a thickness which iscontinuously variable over a considerable length.

By means of this characteristic it is possible in particular to avoidforging, which in conventional processes is often necessary in order tobe able to provide screw threads for the purpose of making joints at theend of a length of tube.

As can be seen in FIGURE 5, the bearing blocks 14, 14, and 14" are eachlikewise made solid to two pistons 31 which move under the action of acompressed fluid.

This device in particular makes it possible to bring the rolls abruptlybackwards as soon as the pressure ceases to prevail in the chamber 17.

It is clearly understood that the embodiment described hereinabove as anexample is not intended as a limitation and that it may undergo alldesirable modifications without thereby departing from the scope of theinvention.

What I claim is:

1. Method of rolling a thin metallic tube from a pierced billet by meansof a rolling mill equipped with a plurality of rolls which cooperatewith a central mandrel for carrying the pierced billet, and with meansfor varying the angular position of said rolls with respect to the axisof said mandrel and for varying the thickness of the tube beingproduced, said method comprising the steps of rolling the pierced billetto a Wall thickness less than 1/11 of the outer diameter of said billetfor the greater part of its length and then changing the setting of saidrolls to reduce the angle between the axes of said rolls and that ofsaid mandrel and produce a greater wall thickness as the trailing edgeof said billet passes through said mill.

2. Method as claimed in claim 1 in which the thickness of the trailingportion of said billet wall is kept greater than 1/11 of the outerdiameter of the billet.

3. Tube rolling mill comprising a central mandrel positioned to beencircled by a tube being advanced axially therealong, a pair ofhousings axially spaced along said mandrel and a plurality of rollspositioned around said mandrel between said housings, each roll beingpivotally and rotatably mounted at one end in one of said housings andat the other end in the other of said housings, at least one of saidhousings being mounted to turn about said mandrel and thereby alter theangular position of the axes of said rolls relative to that of saidmandrel.

4. Tube rolling mill as claimed in claim 3 comprising means forautomatically turning said last mentioned housing when the trailing endof a tube being rolled approaches said rolls.

5. Tube rolling mill as claimed in claim 3 comprising three rollssymmetrically distributed about said mandrel.

6. Tube rolling mill as claimed in claim 3 in which said roll ends aremounted in bearings which are supported in said housing for radialmovement relative to the axis of said mandrel.

7. Tube rolling mill as claimed in claim 3 in which said roll ends aremounted in bearings supported in said housings by fluid pressureactuated means which are movable radially of said mandrel.

8. Tube rolling mill as claimed in claim 3 in which the means forturning the movable housing comprises a photo electric cell positionedto be controlled by the passage of said pierced billet beyond apredetermined point as it travels through the machine.

References Cited UNITED STATES PATENTS 1,713,678 5/1929 Seibert 72-2421,773,748 8/1930 Nelson 72366 2,336,397 12/1943 Harrington 72962,774,263 12/1956 Leufven 72-248 2,868,047 1/1959 Ziiblin 72248 MILTONS. MEHR, Primary Examiner

